The present invention relates to a contact lens for viewing the interior portions of a patient""s eye during a diagnostic examination, or a laser treatment, or surgery. More specifically the present invention relates to a sterile disposable lens, made of a hollow body filled with sterile, transparent and flexible material such as a gel.
Direct viewing of the internal parts of the eye is impossible because light rays coming from internal parts of the eye either undergo total internal reflection at the cornea/air interface and cannot escape the eye or undergo refraction which focus the rays very close to the cornea. In order for an ophthalmologist to view the interior of a patient""s eye, and in particular in order to view the retina or the anterior chamber angle (during routine diagnostic examinations or during laser treatment or surgery), it is necessary to employ a lens that negates the high power of the optical system of the eye.
Many types of ophthalmic diagnostic indirect and contact lenses aimed at this purpose are known. They come in different sizes and shapes, are made of various materials, having different fields of view and are aimed for viewing specific areas of the eye. The diversity of lenses known in the art can be appreciated from the catalogues of well known companies such as Haag Streit, Ocular Instruments, Zeiss, Volk, etc. U.S. Pat. No. 5,165,409 discloses an apparatus for measuring pressure within an eye, the apparatus is capable of providing accurate and reproducible measurements of the intraocular pressure, while permitting the use of disposable sheath for covering the part of the apparatus that touches the eye during measurement. International Publication No. WO 95/19748 discloses a mirrored, hollow lens, filled with a fluid or medium, which reduces the degree of astigmatic focusing which occurs when light or laser light pass through other contact lenses. DE 3032164 discloses an adaptor for use with an objective lens in an ophthalmological microscope comprised of an eyepiece member having an aperture defined therein for containing an impregnating liquid having a refractive index intermediate those of an objective lens and the cornea to be observed and a collar member for supporting the eyepiece member in fixed relation to the objective lens.
Most of the lenses known in the art suffer from a common drawback. They are all designed for multiple-use and between re-uses need to be disinfected or sterilized. It is the practice among persons in the eye care field to posses a limited set of non-disposable lenses that undergo disinfection or sterilization between one patient to another. This practice is in contradiction with the nowadays general trend to employ disposable medical equipment, whenever possible, due to the increasing awareness and demand of both physicians and patients.
Another main drawback common to most of the known diagnostic lenses is the rigid and fixed curvature of their front face (i.e., the face to be facing or contacting the patient""s eye) which cannot be fitted exactly to the specific corneal topography of the individual eye under examination. The practice is to make the frontal curvature a bit steeper than the curvature of an average eye and before applying to the eye to put a small amount liquid on the surface which fills the space between the cornea and the lens when applying to the eye. This procedure is somewhat cumbersome and because the front face is made of a rigid material can sometimes results in scratches or erosions to the patient""s cornea.
An additional disadvantage common to most lenses stemming from the above, is their high cost caused by the relatively expensive materials from which they are fabricated (high quality glass or plastic) and the great care needed to polish the front face in order to obtain the desired curvature.
It is the aim of the present invention to provide a cheap, easy to handle, disposable and sterile ophthalmic diagnostic lens for use in various eye lens applications such as examining procedures and laser treatments and surgeries.
It is another aim of the present invention to provide a contact lens which, while fulfilling the requirements of sterility and disposability, will have a soft and flexible frontal face such that it will have the ability to adopt itself exactly to the shape of the specific eye under examination, thus providing an optimal lens fit. and at the same time will reduce the risk of injury to eye to a minimum.
The present invention relates to a sterile disposable and self adaptable diagnostic lens for the purpose of viewing the interior of a patient""s eye during a diagnostic examination or during therapeutic procedures such as a laser treatment or a surgery. Said contact lens is made from a hollow body, having a front (toward eye) and a back (toward physician) exits, filled with transparent flexible material such as a gel. The back exit, which serves the physician to illuminate the eye and to look into the eye is sealed by a thin transparent window, through which light enters into and comes out of the lens. The front exit, facing the eye, is covered by a removable thin film, to keep the gel in place and to keep sterility. The back transparent window can be flat, curved, prismatic or tilted with respect to the main axial axis of the lens, or a combination thereof.
Attaching the front face of the lens to the patient""s eye, after removing said film, causes the transparent flexible material outer surface to reshape and fit itself exactly to the patient""s eye curvature, thus forming a lens whose curvature negates that of the cornea.
The transparent material filling the lens can be cohesive, i.e., leaving no traces of material on the patient""s eye or adhesive, i.e. leaving some of the material on the eye, upon removing the lens from the eye at the end of the treatment or surgery.
In a special embodiment of the present invention, the material filling the hollow body is in the form of a dry gel or a powder and a predetermined amount of liquid is added to said dry gel or powder to form the transparent flexible material before the lens is to be used.
In a preferred embodiment of the present invention, the hollow body has a shape of a hollow truncated cone (a cone whose point is cut off) wherein its smaller base is the front circular exit (facing the eye) which is covered by the removable film while the larger one is the back face which serves as an optical surface.
The refraction index of the transparent material can be in the range 1.1 to 1.8.
The combination of the transparent flexible material refractive index and the back window""s curvature and thickness is selected according to needs.
According to the present invention the lens can further comprise any optical elements, such as lenses and mirrors, in order to obtain a better and/or magnified image, to reflect the image of peripheral hidden parts of the eye and to increase the field of view.
Keeping the sterility of the lens according to the present invention is achieved by hermetic sterile sealing between the frontal face and the removable film or by packing the whole lens in a hermetic envelope package that keeps sterility.
The so sealed or packed lens undergoes sterilization by any suitable sterilization process known in the art.